Post by Andrei Tchentchik on Jun 17, 2019 11:13:00 GMT 2
(.#199).- The satellites of Elon Musk form a train of stars, unheard of.
The satellites of Elon Musk form a train of stars, unheard of.
By Tristan Vey - Updated on the 31/05/2019 at 22:17
The first 60 satellites of Starlink form a train scrolling in the sky. Movie Vertigo-Youtube.
The show, worthy of a film of SF, is striking. Some astronomers were moved earlier this week, fearing that it would become a threat to the starry sky.
The first 60 satellites of SpaceX's starlink megaconstellation project, deployed last Saturday, offered this week a show that was both grandiose, worthy of a sci-fi film, and disturbing. This cluster of small satellites dropped at 440 km altitude has been so brilliant that it is sometimes visible to the naked eye. We can thus distinguish a train of stars parading in the sky (by clicking on the button "track it" on this page, you can see the position of each satellite at a given moment and its trajectory). Never seen in the history of astronomy, simply. The two videos below taken respectively on May 26th at 11:26 pm, and two hours later, at 1:03 am, in Great Britain, are perhaps the most incredible:
VIDÉO YouTube : SpaceX Starlink satellite...
DURÉE : 1m13s.
The surprise passed, a wind of panic began to blow. If the 12,000 devices of this megaconstellation destined to provide the Internet all over the world are actually put into orbit (which is still far from obvious), the starry sky would be threatened? Remember that even in a sky very spared by light pollution, we never distinguish more than a few thousand stars.
Different astronomers or astrophysicists have been excited about it on Twitter, like Alex Parker or Jonathan McDowell. A particular image has circulated, putting the community in turmoil. We can see the luminous trails left by a shot taken by the Lowell Observatory telescope in Arizona as he tries to observe the galaxy NGC 5353/4:
Lowell Observatory
All this is really scary. Starlink's ballet satellites would undeniably be a problem if they were all so visible ... But different elements must be taken into account. For starters, the satellites are not yet in their final orbit, which will be higher than 100 km at least. Ultimately, they will be half as bright and far from each other. This will remove this striking group effect. The complete constellation will finally spread to 1200 km, at altitudes where most will not be visible. Elon Musk also promised that he would see with his engineers if it was possible to reduce the amount of light reflected by his gear (so-called albedo) to limit the potential for light pollution. In the end, few Satrlink satellites will be visible to the naked eye.
Amateur astronomers do not seem more worried than that. "We do not do very long poses anymore," explains Frédéric Tapissier, president of the association Astronomie du Vexin (AVEX). "We cut the nights into a series of short poses that we then add with software, which allows us to eliminate the photos over which the satellites pass." The problem is indeed not completely new and thousands of objects are already in orbit around us. When you see a star moving in the sky, it's usually a satellite! There is one per minute in the sky. The brightest is undoubtedly the International Space Station. "I do not think megaconstellations will pose a particular problem for us to take beautiful pictures," says Frédéric Tapissier.
On Friday night, SpaceX said the first 60 satellites in its Starlink high-speed Internet constellation were working well and would be less visible from Earth when they reached their final orbit. In its announcement, SpaceX announces that "the 60 satellites deployed their solar panels successfully, generated energy and communicated with the ground stations". "Also, please note that the observability (sic) of the Starlink satellites is dramatically reduced as they mount their orbit at a greater distance and orient themselves with their antennas (...) facing the Earth and their solar panels at the back of the satellite body, "added the company.
The star sky threatened by lighting
As for professional astronomers, they work on extremely small areas of sky. "The chances that a satellite passes precisely on the studied object are almost zero," says Jean-Eudes Arlot, astronomer at the Institute of celestial mechanics and calculating ephemeris. "As for the more systematic sky surveys that are done, they should not have much trouble ignoring these spurious signals that do not look like the objects at all. I do not think there is cause for concern. "
Both passionate people emphasize that the main threat to the starry sky is still the light pollution coming from the ground. In big cities like Paris, it is generally impossible to see more than a dozen stars in the best cases. As for seeing the Milky Way, for example, you really have to be in remote areas to be able to discern it again. A sad reality.
F I N .
The satellites of Elon Musk form a train of stars, unheard of.
By Tristan Vey - Updated on the 31/05/2019 at 22:17
The first 60 satellites of Starlink form a train scrolling in the sky. Movie Vertigo-Youtube.
The show, worthy of a film of SF, is striking. Some astronomers were moved earlier this week, fearing that it would become a threat to the starry sky.
The first 60 satellites of SpaceX's starlink megaconstellation project, deployed last Saturday, offered this week a show that was both grandiose, worthy of a sci-fi film, and disturbing. This cluster of small satellites dropped at 440 km altitude has been so brilliant that it is sometimes visible to the naked eye. We can thus distinguish a train of stars parading in the sky (by clicking on the button "track it" on this page, you can see the position of each satellite at a given moment and its trajectory). Never seen in the history of astronomy, simply. The two videos below taken respectively on May 26th at 11:26 pm, and two hours later, at 1:03 am, in Great Britain, are perhaps the most incredible:
VIDÉO YouTube : SpaceX Starlink satellite...
DURÉE : 1m13s.
The surprise passed, a wind of panic began to blow. If the 12,000 devices of this megaconstellation destined to provide the Internet all over the world are actually put into orbit (which is still far from obvious), the starry sky would be threatened? Remember that even in a sky very spared by light pollution, we never distinguish more than a few thousand stars.
Different astronomers or astrophysicists have been excited about it on Twitter, like Alex Parker or Jonathan McDowell. A particular image has circulated, putting the community in turmoil. We can see the luminous trails left by a shot taken by the Lowell Observatory telescope in Arizona as he tries to observe the galaxy NGC 5353/4:
Lowell Observatory
All this is really scary. Starlink's ballet satellites would undeniably be a problem if they were all so visible ... But different elements must be taken into account. For starters, the satellites are not yet in their final orbit, which will be higher than 100 km at least. Ultimately, they will be half as bright and far from each other. This will remove this striking group effect. The complete constellation will finally spread to 1200 km, at altitudes where most will not be visible. Elon Musk also promised that he would see with his engineers if it was possible to reduce the amount of light reflected by his gear (so-called albedo) to limit the potential for light pollution. In the end, few Satrlink satellites will be visible to the naked eye.
Amateur astronomers do not seem more worried than that. "We do not do very long poses anymore," explains Frédéric Tapissier, president of the association Astronomie du Vexin (AVEX). "We cut the nights into a series of short poses that we then add with software, which allows us to eliminate the photos over which the satellites pass." The problem is indeed not completely new and thousands of objects are already in orbit around us. When you see a star moving in the sky, it's usually a satellite! There is one per minute in the sky. The brightest is undoubtedly the International Space Station. "I do not think megaconstellations will pose a particular problem for us to take beautiful pictures," says Frédéric Tapissier.
On Friday night, SpaceX said the first 60 satellites in its Starlink high-speed Internet constellation were working well and would be less visible from Earth when they reached their final orbit. In its announcement, SpaceX announces that "the 60 satellites deployed their solar panels successfully, generated energy and communicated with the ground stations". "Also, please note that the observability (sic) of the Starlink satellites is dramatically reduced as they mount their orbit at a greater distance and orient themselves with their antennas (...) facing the Earth and their solar panels at the back of the satellite body, "added the company.
The star sky threatened by lighting
As for professional astronomers, they work on extremely small areas of sky. "The chances that a satellite passes precisely on the studied object are almost zero," says Jean-Eudes Arlot, astronomer at the Institute of celestial mechanics and calculating ephemeris. "As for the more systematic sky surveys that are done, they should not have much trouble ignoring these spurious signals that do not look like the objects at all. I do not think there is cause for concern. "
Both passionate people emphasize that the main threat to the starry sky is still the light pollution coming from the ground. In big cities like Paris, it is generally impossible to see more than a dozen stars in the best cases. As for seeing the Milky Way, for example, you really have to be in remote areas to be able to discern it again. A sad reality.
F I N .
